\documentclass{article}
\usepackage{tikz,amsmath}
\usetikzlibrary{arrows.meta}
\usepackage[graphics,tightpage,active]{preview}
\PreviewEnvironment{tikzpicture}
\begin{document}
\begin{tikzpicture}[>=Stealth]
    \draw [->] (-3.5,0) -- (3.5,0) node[anchor=north] {$x$};
    \draw [->] (0,-1.0) -- (0,5) node[anchor=east] {$y$};
    \node at (-0.3,-0.3) {$O$};
    \node at (0.5,0.7) {$(0, 1)$};

    \draw[domain=-2.1:1.3,samples=50] plot (\x, {3.2^\x}) +(0.7, -0.3) node {$y = a^x$} +(0.7, -0.9) node{$(a > 1)$};
    \draw[dash pattern=on 5mm off 2mm] (3, 1) -- (-3, 1) +(0.5, +0.4) node {$y = 1$};
\end{tikzpicture}
\end{document}